A typical gas dispersion configuration for gas deposition chambers (e.g. plasma enhanced deposition chambers, epitaxial reactors, etch chambers, etc.) is illustrated in FIG. 1. Such chambers include a gas inlet 10 at the bottom 11 of chamber, for injection of gas into the chamber. The gas inlet feeds the gas into an annular gas insertion channel 12 that goes around the entire circumference of the chamber bottom wall 11 (for even distribution into the chamber). In order to protect the stepped shaped bottom wall 11 of the chamber, a protective shield 14 is secured onto the bottom wall 11 of the chamber using screws 16. In order to ensure even distribution of the gas, a gas dispersion ring 18 is secured onto the bottom of the chamber using screws 20. The ring covers the annular channel 12, and includes evenly spaced holes 22 extending vertically through the ring 18 and directly over the channel 12, so that gas is evenly and vertically injected into the chamber. After one or more gas deposition processes (which are well known in the art and not further disclosed herein), the protective shield 14 and gas dispersion ring 18 are removed and replaced so subsequent processes are not contaminated.
One problem with the prior art configuration is that it is time consuming to remove and replace the shield 14 and ring 18 after each process, because it takes time to remove and replace all the screws 16/20 used to hold down these parts, and there are two separate parts to remove and replace. Further, the screws 16/20 provide a source of contamination. Finally, the gas exiting the channel 12 is injected vertically upwards from annular gas dispersion ring holes 22, which are already disposed at or near the chamber side walls 24. Such gas injection impinges on the chamber walls 24 causing poor adhesion of deposited etchant (causing particle problems).
There is a need for an improved protective shield and gas dispersion ring configuration that provides more convenient installation and removal, and improved gas injection characteristics.